Make a PR branch

1. Fetch origin, resolve the current and default branches, and inspect commits and working-tree changes against origin/<default>. Stop if there is no work to move.

2. If the current branch is already conventional, stop and use make-pr. Rename another non-default branch only when it is clearly auto-generated or the user asked; otherwise stop.

3. Choose <type>/<short-kebab-description> from the work, using its Conventional Commit type.

4. From the default branch, preserve everything without stashing:

   git switch --no-track -c <new-branch>
   git branch -f <default> origin/<default>
   

   Creating the new branch first keeps every commit reachable and the working tree unchanged; --no-track leaves upstream setup to make-pr.

5. From a placeholder branch, rename it with git branch -m <new-branch>.